It is known in the industry to use position sensing devices to detect angular positions of a rotatable shaft.
Traditionally, mechanical-contacted position sensing devices are used to detect angular positions of a rotatable shaft. However, mechanical-contacted position sensing devices have some shortcomings including mechanical wear, low angle accuracy and reliability and no diagnostic capability.
There has been a proposal to use an electronic sensing system to generate binary signals to reflect angular positions of a rotatable shaft. Specifically, the electronic sensing system includes a sensing device for generating analog electrical signals in response to the rotation of the rotatable shaft and the electronic sensing system further processes the analog signals to generate the binary signals to indicate the angular position of the rotatable shaft. More specifically, a magnet device is attached on the rotatable shaft and adapted to rotate together with the rotatable shaft. The magnet device causes magnetic flux density changes/magnetic field changes to the sensing device while it is rotating around the rotatable shaft. The sensing device generates analog electrical signals in response to the magnetic flux density changes/magnetic field changes and the analog electric signals are then converted into binary signals.
Therefore, there is a need to provide an improved magnet device for generating magnetic flux density changes/magnetic field changes that more accurately reflect the angular position of a rotatable shaft.
There is another need to provide an improved sensing device to generate binary state signals to more accurately reflect the angular position of a rotatable shaft using the magnetic flux density changes/magnetic field changes.